DE 298 18 499 U discloses a mixer for producing pastes from components with different proportions by volume, which has a delay chamber. The latter forms a bypass channel which prolongs the path from an inlet opening to a mixer element and runs along a curve around the longitudinal axis. This mixer constitutes a further development of the dynamic mixer disclosed by EP 0 492 412 A1.
Also known are static mixers, as they are called, which, as opposed to a dynamic mixer, have no moving parts. Mixers of this type are suitable only for mixing and discharging relatively thin substances, cf. EP 0 885 651 A1, EP 0 664 153 A1 or EP 0 584 428 A1.
As distinct from the dynamic mixer, which swirls the components to be mixed, in the static or flow mixer mixing is carried out by repeated stream division.
In the case of mixing with a delay chamber, for reasons connected with reducing the overall length, this is preferably configured in such a way that the paste component flowing in, which enters the mixer longitudinally, is regularly deflected through about 90°. The actual delay section is thus located transversely with respect to the rotatably mounted mixing element, cf. EP 1 099 470 A1.
At the end of the delay section, the paste component either flows directly into the mixing chamber or the paste component enters the mixing chamber offset through about 90°, so that the flow direction of the paste component changes once again.
In this case, the delay chamber can extend both in only one direction with one outlet and in two directions with, correspondingly, two outlets.
The deflection of the entire paste stream of a component induces very high frictional losses in the paste, which increase the flow resistance considerably. The force necessary to convey the pastes, which is transmitted to the pastes via delivery pistons, therefore rises sharply.
It is therefore possible for the dynamic mixers known hitherto to be used only for mixing pastes which have an average consistency and ability to stand without settling. Such pastes usually have a viscosity in the range from 200 to 800 Pas.
However, omitting the delay chamber is not possible, since it is precisely paste with a high ability to stand without settling and a high viscosity in which one component tends to run ahead to a particularly great extent.